| 摘要 |
PURPOSE:To perform a trimming on the resistors located in a semiconductor device even after the semiconductor device has been packaged by a method wherein the operation of an EPROM is controlled corresponding to the resistance value of the resistor on which a trimming is performed. CONSTITUTION:A trimming is performed based on the relation between the control voltage V1-V3 generated on the gate of EPROM 21-23 and the threshold voltage Vth of the EPROM 21-23. To be more precise, when the threshold voltage Vth of the EPROM 21-23 has the voltage value higher than that of the control voltage V3, namely, when the relation between the threshold voltage and the control voltage is Vth>V3, all the EPROM 21-23 are in OFF state, and the trimming on the resistor R0 to be trimmed is not performed. Also, when the threshold voltage Vth of the EPROM 21-23 has the voltage value lower than the control voltage V3 and higher than the V2, namely, they are in the relation of V3>Vth>V2, the EPROM 23 is turned ON, and the resistor R3 is brought in the state wherein it is connected in parallel with the resistor R0 to be trimmed.
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